A hydrate of beryllium nitrate has the following formula: Be (NO3) 2⋅xH2O. The water in a 3.41-g sample of the hydrate was driven off by heating. The remaining sample had a mass of 2.43 g. Find the number of waters of hydration (x) in the hydrate.

The formula is Be (NO3) 2*3H2O. The number of waters in the hydrate is 3

Explanation:

Step 1: Data given

Mass of the hydrate sample = 3.41 grams

Mass after heating = 2.43 grams

Step 2: Calculate mass of water

After heating, all the water is gone. So the mass of water can be calculated by

Mass of hydrate before heating - mass after heating

Mass of water = 3.41 - 2.43 = 0.98 grams

Step 2 : Calculate moles H2O

Moles H2O = mass H2O / molar mass H2O

Moles H2O = 0.98 grams / 18.02 g/mol

Moles H2O = 0.054 moles

Step 3: Calculate moles Be (NO3) 2

Moles Be (NO3) 2 = 2.43 grams / 133.02

Moles Be (NO3) 2 = 0.0183 moles

Step 4: Calculate molecules water

Molecules H2O = 0.054 moles / 0.0183 moles

Molecules H2O = 3.0

The formula is Be (NO3) 2*3H2O. The number of waters in the hydrate is 3